Extract sandboxFilesTreeOptions and buildTreeFromFlatList from
useSandboxFilesTree so callers that need custom TanStack Query behavior
(e.g. refetchInterval) can compose at the call site instead of tunneling
options through the hook. Remove the thin useGetSandboxProviderList
wrapper in favor of inline oRPC queryOptions in the component.
Also remove redundant .input(type<unknown>()) from three no-input GET
contracts—oc already defaults TInputSchema to Schema<unknown, unknown>.
Update frontend to use new backend API:
- save_config now accepts optional 'activate' parameter
- activate endpoint now requires 'type' parameter ('system' | 'user')
When switching to managed mode, call activate with type='system' instead
of deleting user config, so custom configurations are preserved for
future use.
